Producers and distributors of chemicals that are harmful to humans when not properly used take every precaution they can to protect children from exposing themselves to the chemicals. For this reason, there are several patents on child-proof caps which prevent a child from opening a container. For example, U.S. Pat. Nos. 3,706,401 and 3,747,807 describe a child-proof cap for aerosol cans. U.S. Pat. Nos. 3,685,676 and 3,770,153 disclose safety closures for containers of substantially different configuration than an aerosol can.
It is this last group of containers which is the primary concern of the present invention, although it can also be used as a closure for an aerosol can. The last-two-mentioned patents are further described.
In U.S. Pat. No. 3,685,676, the cap disclosed is a dual cap with an outer cup rotatably secured to an inner cup having threads on its inner surface. This cap is removed from the container by pushing inwardly in the center of the top of an outer cup, which in turn flexes upwardly, exposing the depending sidewalls of the inner cup. The inner cup can then be grasped to be unscrewed from the container opening. The force necessary to push the outer cup outwardly is beyond the strength of a child.
On the other hand, U.S. Pat. No. 3,770,153 discloses a cap formed into a unitary body. That is, the outer cup and the inner cup are one structure and not rotatably secured to one another. The inner cup has threads on its inner surface and the outer cup has lugs which engage first a cam surface and then lug recesses on the cam. The inner cup is able to be screwed down as the lugs of the outer cup ride along the cam surface and then fall into the lug recesses. When the cap is to be removed, the outer cup must be squeezed or deformed so that the lugs project from or move out of their lug recesses onto the cam surface. The outer cup is sufficiently stiff so that a child cannot deform it. Additionally, the inner cup must also be significantly stiff so that it does not deform so much that is is in fact not sealing the container opening.
The present invention, however, will illustrate and describe a child-proof cap that does not require adult force to remove it from a container, but only requires the person who opens the container to have adult-sized hands. This feature becomes extremely important when an adult who has arthritis wishes to open a container with a child-proof cap. Another embodiment of the invention will illustrate that the inner cup does not have to be substantially stiff, and, the neck portion on the container can be significantly thinner than before. An alternate embodiment will indicate a child-proof cap resulting in a saving of approximately 50% of the material in the outer cup.